Dec. 16: Does your cellphone suddenly go on the blink when the chief minister is around' It did in Behrampore, where Buddhadeb Bhattacharjee went for a few hours yesterday.

To the dismay of the mobile phone users in the district headquarters of Murshidabad, the screens on their sets went blank at 2.30 pm, quarter-of-an-hour before the chief minister arrived to address a rally.

According to intelligence sources, the radio signals on a cellular network can be used to trigger explosions and track wireless communication.

Deputy inspector-general of police, Murshidabad range, D.P. Tarenia said they had taken “unprecedented security measures” ahead of the chief minister’s visit but refused to go into details. “It is a border district and several ISI activists were picked up recently. Investigations revealed the ISI had penetrated deep. The chief minister is high on their hit list and we did not wish to take chances.’’

In the run-up to the rally, the police consulted the blue book — an elite security manual — to provide cover to the “VVIP”. Even the Union home ministry was kept informed about the security setup.

The cellphones returned to life after the chief minister’s 13-car convoy entered Nadia around 5.30 pm yesterday.